Wireless cellular communication networks incorporate a number of mobile UEs and a number of NodeBs. A NodeB is generally a fixed station, and may also be called a base transceiver system (BTS), an access point (AP), a base station (BS), or some other equivalent terminology. As improvements of networks are made, the NodeB functionality evolves, so a NodeB is sometimes also referred to as an evolved NodeB (eNB). In general, NodeB hardware, when deployed, is fixed and stationary, while the UE hardware is portable.
In contrast to NodeB, the mobile UE can comprise portable hardware. User equipment (UE), also commonly referred to as a terminal or a mobile station, may be fixed or mobile device and may be a wireless device, a cellular phone, a personal digital assistant (PDA), a wireless modem card, and so on. Uplink communication (UL) refers to a communication from the mobile UE to the NodeB, whereas downlink (DL) refers to communication from the NodeB to the mobile UE. Each NodeB contains radio frequency transmitter(s) and the receiver(s) used to communicate directly with the mobiles, which move freely around it. Similarly, each mobile UE contains radio frequency transmitter(s) and the receiver(s) used to communicate directly with the NodeB. In cellular networks, the mobiles cannot communicate directly with each other but have to communicate with the NodeB.
The Global System for Mobile Communications (GSM: originally from Groupe Spécial Mobile) is currently the most popular standard for mobile phones in the world and is referred to as a 2G (second generation) system based on TDMA (Time Division Multiple Access) mobile air interface. W-CDMA (Wideband Code Division Multiple Access) is a type of 3G (third generation) cellular network. W-CDMA is the higher speed transmission protocol designed as a replacement for the aging 2G GSM networks deployed worldwide. More technically, W-CDMA is a wideband spread-spectrum mobile air interface that utilizes the direct sequence Code Division Multiple Access signaling method (or CDMA) to achieve higher speeds and support more users compared to the older TDMA signaling method of GSM networks.
In GSM, the radio subsystem is required to support a certain number of logical channels that can be separated into two categories: i) the traffic channels (TCH's); and ii) the control channels. Traffic channels (TCH's) are intended to carry either encoded speech or user data in circuit switched mode. Five general forms of traffic channel are defined:                i) Full rate traffic channel (TCH/F). This channel carries information at a gross rate of 22.8 kbit/s.        ii) Half rate traffic channel (TCH/H). This channel carries information at a gross rate of 11.4 kbit/s.        iii) Enhanced circuit switched full rate traffic channel (E-TCH/F). This channel carries information at a gross rate of 69.6 kbit/s including the stealing symbols.        iv) 8-PSK full rate traffic channel (O-TCH/F). This channel carries information at a gross rate of 68.4 kbit/s.        v) 8-PSK half rate traffic channel (O-TCH/H). This channel carries information at a gross rate of 34.2 kbit/s.        
Several combinations of these traffic channels may used to transfer speech for a typical cell phone voice call, such as full rate traffic channel for speech (TCH/FS). Control channels are intended to carry signaling or synchronization data. Four categories of control channel are defined: broadcast, common, dedicated and CTS control channels. The general operation of TDMA radio access network is described in “3rd Generation Partnership Project; Technical Specification Group GSM/EDGE Radio Access Network; Multiplexing and multiple access on the radio path (Release 7)” (3GPP TS 45.002 V7.7.0, 2008-05) and in other related 3GPP specifications.